There are certain phone calls a father dreads receiving from their teenage son. This was one. "Uh, hullo Dad, it's me, you know… Rufus." I recognised my 14-year-old's laconic drawl and total absence of consonants, but it was good of him to tip me off. "Well, you know that nice car you've got this week?"

Do you mean the blisteringly fast, scarlet-hued R8 Spyder with a 525bhp, direct-injection V10 engine and four-wheel drive? I chortled.

"Yeah, that one," he replied. And then I heard him pause and swallow. "Well, me and my friends were mucking about in it and, like, sorry and everything, but I think we've broken it…"

It turned out that Rufus and his mates hadn't been thrashing the £116,660 supercar around the block, but had just been sitting in it, roof down, music up… and had somehow locked the roof in a half-up position. I couldn't really blame him. It's such a magnetically attractive car it's hard to keep your hands off it.

The new Spyder, which introduces a bigger engine and folding canvas roof to the mega-successful R8, which was launched on a grateful nation two years ago, has a sort charisma forcefield that stops passersby mid-stride. Peering out of my front window at the supercar crouching under the yellow street lamps, it became a game to spot anybody who didn't pause and gawp. School kids dug out their phones to snap pictures of themselves doing gang signs next to it, men peered through the windows. When two teenage girls marched past arm in arm, without even registering it, I almost cheered.

When the Spyder's hardtopped sister with its distinctive twin side blades was released it was instantly buried in an avalanche of accolades. I can think of few other cars that had so many motoring journalists pinning their colours to the mast and, hands on hips, proclaiming: "This is the best two-seater I've ever driven." But now we have the Spyder – classier, curvier, lighter, faster and a convertible… It looks like the best has just got bester.

The folding roof is a masterclass in origami and tucks itself behind the seats in less than 20 seconds, even at speeds of up to 31mph (try at 32mph and, who knows, you might take off like a parasailer). It has a boot, too, that's big enough to store a pair of boots. If you are thinking of buying a Spyder – it's the most expensive car Audi makes – you'll need to ask yourself one question. Can you cope with the adulation? It's a car for exhibitionists. But then who wouldn't want to show off in a car that boasts such electrifying performance.

It is so low and quick it's like sitting in a bobsleigh. Its swooping side-scoops mean you stick to the road like insects to fly paper. The interior is surprisingly basic. Yes, there's plenty of leather about and the square-bottomed steering wheel and touch points all have a glossy feel to them. There are parking sensors, LED headlights, satnav, Bang & Olufsen stereo and a nifty phone mic in the driver's seatbelt, but despite all its pyrotechnics, the Spyder has a purity of purpose which makes you believe you aren't, in fact, a big-headed show- off. You just care deeply about things like, well, going very fast.